\usemodule[zhfonts]
\startMPpage
input snail.mp;
Node a;
a := proc("打酱油");
enrich(a);
draw a;
tagged_flow("\rotate[90]{路过}", "left", .65)
  walk(a.E, ((_E_ 0) >>> (_N_ .5a.height)
  >>> (_WW_ a.width) >>> (_SS_ a.height) >>> (_E_ .5a.width)), a.S);
\stopMPpage
